This invention relates to an apparatus that will maintain heated water at remote hot water faucets in residential and small commercial buildings.
Considerable time and water are wasted daily awaiting hot water at faucets remote from the heater. In some plumbing installations this can take up to two minutes, and results in wasting 10 to 12 liters of water per occurrence and up to 8,000 liters of water per year in the average home. Many methods have been developed for resolution of this issue. The two primary approaches are: (1) an auxiliary remote water heater, either under the sink near the faucet, or in the basement below the sink, and (2) water circulation systems that bring heated water from the existing water heater to the faucet via the normal hot water pipes and circulate it back to the heater through a separate return line, thereby maintaining heated water at the remote hot water faucet and all hot water faucets between the heater and the remote faucet.
Auxiliary heaters like that described in U.S. Pat. No. 4,236,548 to Howard can be used for this purpose, but initial purchase cost, and the high cost of installation driven by the need to connect gas or electricity has limited their acceptance. Some auxiliary heaters are made for another purpose entirely, which is to provide very hot water at the sink through a separate faucet. Water supplied by these devices is hot enough to be used for soups and instant coffee and tea without additional heating. This concept and purpose is unrelated to the present invention.
Water circulation systems are generally grouped as convective or pumped circulation. Convective circulation systems as described in U.S. Pat. No. 3,929,153 to Hasty and U.S. Pat. No. 2,255,460 to Weaver employ water supply pipes to the remote faucet that slope upward and return lines from the faucet back to the heater inlet that slope downward. This arrangement is difficult to implement, especially when retrofitting existing buildings. Many of these installations, as described by Hasty, have the disadvantage of hot return line water being mixed with cold water in the cold water pipe. This lukewarm water must then be wasted if cold water is desired at a cold water tap. Heating of the cold water is a common problem in water circulation systems, and many installations do not lend themselves to the replumbing necessary to minimize it, nor does the owner want to bear the expense of replumbing. In addition, concerns are now being voiced as to the health risk associated with the use of water that has been heated for human consumption due to the increased solubility of lead and copper in heated water.
Pumps used for recirculation systems, as described in U.S. Pat. No. 3,669,351 to Meier et al. and U.S. Pat. No. 4,142,515 to Skaats, are functional, but require electrical power which may not be available in the desired location. These systems are very complex, using motors, seals, switches, bearings, timers, and control electronics, and are much more subject to failure. Operational costs to run the pump will be incurred, and a pump may produce noise that is objectionable to some people. The Skaats reference recognizes the undesirable tendency of heating of the cold water in the cold water distribution pipe by the mixing of warm water from the return line in pumped water circulation systems.
The aspirator activated hot water circulation systems taught by the present inventor in his U.S. Pat. Nos. 5,331,996 and 5,518,022 will perform well in almost all installations, whether or not convective flow is strong, and also those installations in which only a small return line can be installed. The single chamber concept of the present invention, having a lower manufacturing cost and being simpler to install, will perform well in a large majority of domestic applications, in addition to maintaining separation between warm return line water and cold water being supplied to cold water faucets. The small size of the present invention allows for installation in smaller spaces. The water circulator of the present invention is installed in the water supply pipe leading only to the water heater, leaving cold water pipes untouched in most applications. Local rerouting of the heater supply pipe may be required in some existing water systems. This extremely simple design can be fabricated with lower material costs, simpler tooling and machinery, and will require no sophisticated couplings to assemble.